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Change hue gradually



  • Hi!

    does anybody has a good idea on how to change the hue of an image gradually? (not in time but in space)
    I mean for example, to have the stage with its original hue (0º) on the left, and gradually modify it till it reaches 360º on the right?
    cheers!

  • Tech Staff

    use the same numeric data you are using to move the image to adjust the HSB.
    Or if you are talking about a Hue gradient.. you could apply a gradient (a few Mac actors... I think there is FreeFrame for PC as well) as an overlay?



  • I am talking about a hue gradient yes, but I do not find any "hue gradient" actor or similar in my pc´s isadora.



  • I would make a movie or an image if that is suitable with a mask. You can use the second layer to mask one version of colours over the other, with a still you could just shift it left to right, with a movie you can do whatever you want. This is pretty similar to the way you would do it in post and should give you very precise control over the output. Blurs will feather the edge of your mask live if need be.

    Alternately you can of course pre-render the effect (providing it is not on a live feed).
    Fred


  • Hi Fred and thanks for your answer

    I am working with live feed material from a video camera.
    It sound like you have a solution, but I cannot understand what you suggest. Very probably my lack of technical terminology and experience makes it difficult for me.
    could you be more specific / show me an example?
    thanks!


  • Ok, here is a fast example with no media. The source image in this case is a video in watcher, it outputs twice to the aplhamask as a foreground and a background, but one has the HSL adjust actor in between to mimic the destination gradient. It works as a wipe now as the Mask, which is just a shapes actor with a blur just moves from left to right.

    Instead of the white square with a blur that is fed into the mask you can use any greyscale image, where the image is white you will see the foreground and where it is black you see the background. You can create a movie or an image with the correct gradient (instead of the small gradient generated from the blur). You can either wipe the still from left to right, or create a movie with the movement of the gradient you want in it. If you need a static gradient you can just make that image. You can also fade the mask in and out by fading the source of the mask image.
    This is pretty inefficient as the HSL adjust actor uses a lot of resources, as does the blur. This way is also done with pixels on the CPU which is less than perfect. You can use QC actors to do this on your GPU, or in the upcoming version of Isadora you should be able to do this all on your GPU with either built in actors or freeframeGL actors that have the same functions as the ones I used in this sample.

    bdd3d4-alpha-wipe.izz 2cd3a0-alpha-wipe.izz



  • that is pretty straight forward!

    plus, it helps me understanding the concept of "mask"
    super. thank you so much!


  • ey ey!

    I havent found a related hsl adjust actor in the freeframe folder of izzy 2.0
    I also do not fully understand the apparition of the folder freeframeGL and its use, since it is empty. I am missing something. Could somebody enlight my way?
    :)

  • Tech Staff

    FreeframeGL is the next generation of freeframe plugins. They use the video card to process effects rather than relying on the cpu. Providing much better performance.

    These effects are available from a number of online resources. 
    An official listing of freely available and supported plugins is being made, and will be available soon.
    In the meantime the official test effects are here: http://sourceforge.net/p/freeframe/svn/HEAD/tree/trunk/FFGL-SDK/binaries/ Many others are available online both for free and for purchase.
    Another option for color correction is now available within the mapper. There is RGBA color of each element.
    http://troikatronix.com/support/kb/projection-mapping-in-isadora/


  • great

    I will be expecting this very usefull list!

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